Anti cancer drugs may selectively modify normal as well as tumor cell (affect membranes through modification of lipid synthesis, alter interferon induced protective mechanisms, influence free radical protective mechanisms and inhibit DNA synthesis) and thus affect NK activity toward tumor cells as well as the susceptibility of tumor cells to NK lysis. The main line investigation will focus on how Adriamycin (ADM) and its congener Daunomycin (DM) affect individual components of the NK system as well as how they affect various tumor cells susceptibility to NK lysis. Furthermore, since these antibiotics have been shown to cause cellular and membrane damage through lipid peroxidation, various biochemical parameters in normal and neoplastic cells will be correlated with functional changes in NK activity.